Ester end blocked polysiloxanes



Patented Oct. 5, 1 954 UNITED STATES PATENT OFFICE ESTER END BLOCKED POLYSILOXANES Leo Harry Sommer, State College, Pa., assignor to Dow Corning Corporation, Midland, Mich., a corporation of Michigan No Drawing. Application May 24, 1951, Serial No. 228,121

4 Claims.

ROzCCHzCI-IzSi (CH3) 20[ (CH3) 2 SiO] nSl (CH3) 2CH2CH2CO2R Where R is an alkyl radical and n has a value of at least one. The above materials may be prepared by copolymerizing cyclicdimethylsiloxanes such as octamethylcyclotetrasiloxane with a disiloxane of the formula [RO2CCH2CH2 (CH3) 281120 The copolymerization may be carried out in a normal manner for copolymerizing triorganoand diorganosiloxanes. Preferably the catalyst employed is an acid.

The above ester disiloxanes may be prepared by esterifying the corresponding dicarboxylicdisiloxanes with an alcohol of the formula ROI-I. For this purpose any alcohol in which R is alkyl may be employed and is included Within this invention. For example, methyl, ethyl, octyl and stearyl alcohols are operative. The disiloxanedicarboxylic acids above shown are described and claimed in the applicants copending application Serial Number 155,784, filed April 13, 1950, now Patent 2,589,446.

The following examples are illustrative only and are not to be construed as limiting the invention.

Example 1 375.6 grams of the acid HOOCCHzCI-IzSi (CH3) 2OSi(CH3) 2CH2CH2COOH 2 liters of absolute ethyl alcohol and 25 ml. of concentrated I-ICl were refluxed for 18 hours. At the end of this time, the water-ethanol azeotrope was distilled. The remaining ethanol was removed and the product was vacuum distilled. There was obtained 407 grams of the ethylester boiling 153 C. at 5 mm. having a density at 20 C. of 1.4340. This represented a 90 per cent yield of the ester Whose formula is C2H5OOCCHzCI-I2Si (CH3) 2OSi (CH3) 2 CHzCHzCOOCzI-Is 104.5 grams of this ester, 23.9 grams of octamethylcyclotetrasiloxane and 3 ml. of sulfuric acid were mixed and stirred at room temperature for 14 hours. 8 ml. of water were added and stirring was continued for an additional hour. The organic layer was separated, was washed once with 5 per cent sodium bicarbonate solution and once with water. The organic layer was dried over anhydrous sodiumsulfate. 30 ml. of benzene were added to the partially dried material and the water-benzene azeotrope was distilled. The residue was distilled under vacuum and the following compounds were isolated:

CzHsOzCCHzCI-Iz (CH3) 2SiO' (CH3) 2SiOSi CH3) zCHzCI-IzCOzCzHs boiling point 174 C. at 7 mm., 12 1.4288, D4 .9787 and molar refraction 107.67;

boiling point 186 C. at 7 mm., n 1.4257, D4 .9796 molar refraction 126.29; and

boiling point 190 C. at 4 mm., 11 1.4245, saponification equivalent 277. There remained a residue which was composed of a mixture of higher polymers having more than 3 dimethylsiloxane units in the chain.

That which is claimed is:

1. RO2CCH2CH2(CH3) 2SiO (CH3) 2 slO]nSi(CH3) zCHzCI-IzCOzR where R is an alkyl radical and n has a value of at least 1.

2. A compound in accordance with claim 1 where R is ethyl and n is 1.

3. A compound in accordance with claim 1 where R is ethyl and n is 2.

4. A compound in accordance with claim 1 where R is ethyl and n is 3.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,550,205 Speier Apr. 24, 1951 2,570,090 Barry et al Oct. 2, 1951 2,589,446 Sommer Mar. 18, 1952 OTHER REFERENCES Gold et al.: J. A. C. 3., vol. 71, page 2874 (1948).

Lommer et al.: Ibid., vol. 71, page 1509 (1949).

Sommer et al.: Jour. Am. Chem. $00., vol. 73, February 1951, page 882. 

1. RO2CCH2CH2(CH3)2SIO$(CH3)2 